Mold inhibitor for photographic elements



40 turally as follows:

Patented Dec. 24, 1940 PATENT OFFlC-E MOLD INHIBITOR FOR PHOTOGRAPHI ELEMENTS Cyril J. Stand and Catherine Salo Popper, Rochester, N. Y., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation oi New Jersey No Drawing. Application December 27, 1939,

' Serial No. 311,196

9 Claims.

This invention relates to antiseptics for photographic gelatins and emulsions, and to a method for preventing bacterial growth in such gelatins and emulsions.

'5 Heretofore, a number of mold growth inhibitors have been employed in photographic gelatins' and emulsions to prevent the gelatin, the emulsion and the product, a photographic film, from being attacked by bacterial action. Such 10 inhibitors as formaldehyde, phenol, thymol, and the esters of pehyd'roxybenzoic acid, known as parasepts, such as methyl, ethyl, propyl, butyl, and benzyl parasept, mucochloric and mucobromic acids have been previously employed for these purposes in the prior art.

While these inhibitors for the most part are satisfactory, we have discovered another class of antiseptic compounds some of which have proved to be superior to those listed above in inhibiting bacteriabgrowth on such photographic materials.

We have found that the class of compounds which may be termed the pseudo esters of halogen substituted aldehyde acids are excellent inhibitors. In particular we have found that the pseudo methyl and ethyl esters of m'ucochloric acid have greater mold inhibiting properties at low concentrations then do the above listed antiseptics. Other compounds of this type which are satisfactory as inhibiting agents are: pseudo butyl ester of mucochloric acid, psuedo methyl ester of mucobromic acid, pseudo ethyl ester of mucobromic acid, and pseudo n-butyl ester of mucobromic acid.

These compounds may be produced according to the procedure of Simonis, Berichte der Deutschen Chemischen Gesellschaft, vol. 34 (1901), page 509.

The general type of reaction is shown struc- Cl.C.CHO 01.0.00 H2804 +CH3OH L /0 0]. .COOH CI. .CHOC-H: 45 Muoochloric Pseudo methyl acid ester 0! mucochloric acid mccno Br.C.CO

H1804 CHzOH -r /O 50 Br. .0001: Br.C.CHOCHi Pseudo methyl ester of muw bromic acid To form the other above mentioned ethyl and 55 butyl pseudo esters, the corresponding alcohols are employed in the reaction in place of methyl alcohol.

These pseudo esters are soluble in ethyl alcohol and can be added to and incorporated in the gelatin when it is in a water solution as described ,5 in the following examples:

Example I i To 1000 parts of a 10% gelatin solution adjusted to a pH of 7.5 is added 0.10 gram of pseudo 10 methyl ester of mucochloric acid dissolved in 5 parts of ethyl alcohol. The solution is stirredto distribute the inhibitor therethrough and the gelatin is then protected against mold growth.

Example II 15 Example III 2.5

1000 parts of 10% gelatin solution having a pH of 7.5 are mixed with 0.40 gram of pseudo methyl ester of mucobromie acid dissolved in 5 parts of ethyl alcohol. .As shown in the follow- 30 ing table. this ester is an eflective mold inhibitor at this concentration.

Example IV 1000 parts of 10% gelatin solution having a 35 pH of 7.5 are mixed with 0.40 gram of pseudo nbutyl ester of mucobromic acid in ethyl alcohol. At this concentration of ester no mold growth will occur.

Example V 1000 parts of 10% gelatin solution having a pH 40 of 7.5 are mixed with 0.80 gram of pseudo ethyl ester of mucob'romic acid in ethyl alcohol. Mold growth in the gelatin is prevented at this concentration.

Example VI We have employed these pseudo esters succassfully in emulsions. "To about 5 cc. of ethyl alcohol there was added 0.10 gram of pseudo methyl ester of mucocliloric acid to form a solution of the ,ester'in the alcohol. This solution was addedyto 225 grams of a high speed, high contrast photographic emulsion (containing about 7% gelatin), and after mixing the solution of the inhibitor with the emulsion the emulsion was coated on a transparent cellulose acetate support. A similar emulsion to which no inhibiting agent had been added was coated on a similar support, and the two emulsions were tested for bacteria formation. No mold growth occurred on the emulsion layer containing the inhibitor but some spotting due to mold formation was noted on the emulsion which did not contain an antiseptic.

One method of determining the eflicacy of the pseudo esters of the halogen substituted aldehyde acids is as follows: To each of 6 test tubes were added the 10% gelatin solution adjusted to a pH of 7.5 containing the inhibitor to be tested in such proportion to give the following series of concentrations per liter of gelatin solution 0 (plain gelatin solution of a pH of 7.5 having no inhibitor), 0.05, 0.10, 0.20, 0.40, and 0.80 grams of the inhibitor per liter of gelatin.

These solutions are compared with gelatin solutions containing varying proportions of phenol and thymol. 0.2 gram of phenol and 0.02 gram of thymol were added to 100 cc. of the gelatin solution. The concentrations were adjusted to the following ratios: 0.125 g. phenol/0.0125 g. thymol; 0.25 g. phenol/0.025 g. thymol; 0.5 g. phenol/0.05 g. thymol; 1 g. phenol/0.1 g. thymol and 2 g. phenol/0.2 g. thymol.

What we claim is:

1. A photographic element containing gelatin 4. A photographic element containing a gelatin and having as a bacteria inhibiting agent pseudo ethyl ester of mucochloric acid incorporated therein- I 5. The method of preventing bacteria growth in gelatin which comprises incorporating therein a pseudo ester of a halogen substituted aldehyde acid.

6. The method of preventing'bacteria growth in a photographic gelatin which comprises incorporating therein a pseudo ester of mucochloric acid.

'l. The method of preventing bacteria growth in a. photographic element containing gelatin --no growth oi bacteria.

It will be noted that in the case of methyl and ethyl mucochloric acids, the effective concentrations to prevent bacterial growth are one-halt that required when mucochloric acid is used. These compounds represent an increase in effectiveness of from four to eight times that obtained with the esters of'p-hydroxybenzoic acid, known as parasepts, and are more effective than formaldehyde, or mixtures of phenol and thymol, as shown in this table.

The amount of inhibitor employed in accordance with our invention may 'vary from about 0.10 to 0.80 gram to 1000 cc. of gelatin solution.

Comparative table Concentrations (grams per liter) Phenol-thymol mixture f}? .125/.0i25 251.025 .sma- 1g./.1- 2;.12

+1 +1 v. sl.+ v. sl.+

.o-piai Addenda gmfin .05 l0 .1) .40 .U

Methyl parasept +1. +1. +1. +1. +1. Ethyl lparasept.-- +1. +1. +1. +1. sl.+ Propy parasept-- +1. +1. v. sl.+ gum parase t i1. 81 Skit sl rytt m; c enzy M L in Bad +1. I +1. v. sl.+ Pseudo methyl ester of mucochloric acid +1. sl.+ Pseudo ethyl ester oi mucochloric acid +1. sl.+ Pseudo hutyl ester of mueoehloric acid +1. sl.+ Mucobromic acid +1. +1. sl.+ Pseudo methyl ester of mucobromic acid +1. +1. 1 +1. Pseudo ethyl ester oi mucobromic acid. +1. +1. +1. sl.+ Pseudo n-hutyl ester oi mucobromic acid +1. sl.+ Formaldehyde +1.

+i.- ueiaction and bacterial growth. sl.+- slight growth oi bacteria. i v. sl.+-very slight growth oi bacteria.

which comprises incorporating therein a pseudo ester of mucobromic acid.

-'8. The method of preventing bacteria growth in-a photographic element containing gelatin which comprises incorporating therein a pseudo methyl ester of mucochloric acid.

9. The method of preventing bacteria growth in a photographic element containing gelatin which comprises incorporating therein a pseudo ethyl ester of mucochloric acid.

cyan. J. snap. CATHERINE BALO POPPER. 

